Inertia-damper for electric measuring instruments.



No; 755,792. 4 Q PATENTED MAR. 29, 1904.

. W. H. PRATT.

INERTIA DAMPER FOR ELECTRIC MEASURING INSTRUMENTS.

. APPLICATION FILED MAR. 14. 1902. N0 MODEL.

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IND-755,792- PATENTED MAR. 29, 1904 W. H. PRATT. I

INERTIADAMPER FOR ELECTRIC MEASURING INSTRUMENTS.

APPLIOATIONIILED IAR.14.1902.

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' UNIT D STATES? Patented March 29, 1904.

PATENT OFFICE.

WILLIAM II. PRATT, OF LYNN, MASSACHUSETTS, ASSIGNOR To GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

lNERTlA-DAMPER FOR ELECTRIC MEASURING-INSTRUMENTS.

SPECIFICATION forming part of Letters Patent No. 755,792, dated March 29, 1904.

I Application filed March 14-, 1902.

To all whom it may concern:

Be it known that I,WILLIAM H. PRATT, a'citizen of the United States, residing at Lynn,

damping the oscillations of the moving element, which changes its position with variations in the current.

The invention consists in a weight or weights having a frictional connection with the moving element, so that the inertia of the weight or weights prevents it or them from moving simultaneously with the moving element, but the energy of the moving element is consumed partly in the heat of friction between the moving element and the weight and partly in setting the weight in motion. Its inertia then prevents it from instantly responding to a backward movement of the moving element, so that the friction between these oppositely-moving parts tends to quickly check them both. The moving element is thus free to respond promptly to any change in the current, but its oscillations are rapidly damped by the weight.

In the accompanying drawings, Figure 1 is a front elevation of a measuring instrument equipped with my inertia-damper. Fig. 2 is a cross-section of the same on the line 22, Fig. 1. Fig. 3 is a cross-section of the same on the line 3 3, Fig. 1, on a larger scale. Fig. 4 shows one system of weights on a section takenon the line 4 4, Fig. 3. Fig. 5 shows another system of weights on a section of the line 5 5, Fig. 3.

The instrument to which my invention can be applied may be of any desired construction. In the drawings I have shown an inclined coil voltmeter, having a base A,

cover B, provided with a glazed opening 6 to expose the scale C, an inclined coil D, arma- Serial No.98,237. (N0 model.)

ture E, index-needle F, and coiled spring Gr bular spindle has an internal collar h, having an easy-turning fit on the inner spindle..

On the tubular spindle is :mounted loosely a collar L, preferably retained in position by flanges k on the' spindle. The collar carries arms L, on which are weights-L preferably adjustableas, for instance, by making the weights in the form of nuts screwing onto the ends of the arms. I

Secured to the inner spindle K on'the part extending beyond the tubular spindle is a collar M, carrying arms M, each provided with an adjustable weight M The weights L and M are so adjusted that they are perfectly counterbalanced around the common axis of the spindles H and K. It will be noted that the collar L with its weights and the inner spindle K with its weights are connected with the tubular spindle H merely by the friction between said parts.

The operation of the device is as follows: When the instrument is energized, the armature tends to turn the tubular spindle and the needle rapidly toward the indicating position against the tension of the spring G. In so doing it leaves behind the weighted parts; but the friction between said parts and the tubular spindle causes the energy of motion of the latter to be dissipated in heat and in imparting movement to the weights. Should the being no drag between the armature-spindle and the weighted parts. This makes an excellent dead-beat instrument.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In an indicating instrument, the combination with an arbor and a pointer, of means loosely mounted on said arbor for preventing the vibration of the pointer, substantially as and for the purpose specified.

2. An electric measuring instrument provided with a vibratory pointer and a damper consisting of a part having inertia and movable independentlyof the indicating element of said instrument, said part being frictionally connected with the indicating element.

3. In an electric measuring instrument, the combination with the vibratory indicating element, of a damper comprising a weighted part counterbalanced with reference to and mounted on the axis of said element, and movable independently of said element and having frictional connection therewith.

4. In an electric measuring instrument, the combination with the vibratory indicating elemen t, of a weighted part counterbalanced with reference to the axis of said element, said part being freely movable around said axis independently of the indicating element, and having frictional connection with said element.

5. In an electric measuring instrument, the combination with a vibratory indicating element, of a damper comprising a weighted part counterbalanced with reference to the axis of said spindle, and having a frictional connection with said spindle so as to be movable independently thereof.

6. In an electric measuring instrument, the combination with arotatable tubular spindle,

of a weighted collar having a frictional con- 4 nection therewith.

7. In an electric measuring instrument, the combination with a spindle, of a collar loosely mounted thereon, and weighted arms on said collar counterbalanced around the axis of said spindle.

8. In an electric measuring instrument, the combination with a tubular spindle, of a collar loosely mounted thereon, weighted arms on said collar, an inner spindle, and weighted arms on said inner spindle.

9. In an electric measuring instrument, the combination with two concentric independent spindles, of weights concentric with said spindles and secured to one of them.

10. In an electric measuring instrument, the combination with two concentric independent spindles one of which is freely rotatable on the other, of weights concentric with said spindles, some of said weights being secured to one spindle and the rest loosely mounted on the other.

11. In an electric measuring instrument, the combination with a tubular spindle having a pivot at one end and an internal collar at the other, of an inner spindle having a bearing in said pivot and collar and extending beyond the end of the tubular spindle, a collar loose on the tubular spindle, a collar fast on the extended portion of the inner spindle, and arms on each collar carrying adjustable weights.

In witness whereof I have hereunto setmy hand this 12th day of March, 1902.

WILLIAM H. PRATT.

Witnesses:

DUGALD MoK. MoKILLoP, JOHN A. MCMANUS. 

